The present invention relates generally to agricultural self-propelled windrowers, and more particularly to a rear axle suspension system for such machines.
Self-propelled windrowers have been used in farming operations for several decades. Generally, the self-propelled windrower is designed to cut and process hay and other crops. More specifically, a windrower of the type under consideration here includes a tractor and a separate header. The tractor has a pair of drive wheels on the forward end and a pair of pair of tricycle-like wheels on the rear end. The wheels support a main frame that carries the engine between the wheel pairs and a drive train. A cab provides an enclosed environmentally controlled operator's platform generally above the drive wheels. A variety of crop-harvesting headers are selectively attachable to the forward end of the unit to provide the operator with a choice of tools with which to handle the crops.
In past designs, the rear axle was a single beam (known as a “walking beam”) with very little suspension to ease the ride for the operator. Substantially every obstacle encountered by the rear wheels transmitted a “bounce” or vibration directly through the chassis to the operator's platform, making the ride uncomfortable and tiring, and thus resulting in lower field operation speeds. It is a unique characteristic of this type windrower that when driven without the significant weight of a header, the majority of the weight is shifted to the rear wheels. This causes the rear of the unit to squat and it becomes difficult to turn because the tail forks cannot freely pivot.
It would be a significant advantage in this technology to solve the above-identified problems by providing a suspension system that provides a comfortable ride for the operator during field operation, with higher operation speeds, yet allows safe and effective operation when the unit is driven without a header.